feat: add leaveGroup, addGroupMember, removeGroupMember, setConversationMuted/Pinned

- ImSDK: leaveGroup removes current user from group via DELETE /groups/{id}/members/{userId}
- ImSDK: addGroupMember / removeGroupMember for admin operations
- ImSDK: setConversationMuted / setConversationPinned exposed from ImDatabase methods
- ImSDK: fetchGroupHistory uses new /messages/group-history/{groupId} endpoint

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/im/src/ImSDK.ts

@@ -219,6 +219,28 @@ export const ImSDK = {
     return Array.isArray(res) ? res : (res.content ?? [])
   },
 
+  async addGroupMember(groupId: string, userId: string): Promise<ImGroup> {
+    const config = getConfig()
+    return apiRequest<ImGroup>(`/api/im/groups/${encodeURIComponent(groupId)}/members`, {
+      method: 'POST',
+      params: { appId: config.appId },
+      body: { userId },
+    })
+  },
+
+  async removeGroupMember(groupId: string, targetUserId: string): Promise<ImGroup> {
+    const config = getConfig()
+    return apiRequest<ImGroup>(
+      `/api/im/groups/${encodeURIComponent(groupId)}/members/${encodeURIComponent(targetUserId)}`,
+      { method: 'DELETE', params: { appId: config.appId } },
+    )
+  },
+
+  async leaveGroup(groupId: string): Promise<void> {
+    if (!_currentUserId) throw new Error('[ImSDK] Not logged in')
+    await ImSDK.removeGroupMember(groupId, _currentUserId)
+  },
+
   async fetchGroupHistory(groupId: string, page = 0, size = 50): Promise<ImMessage[]> {
     const config = getConfig()
 
@@ -241,7 +263,7 @@ export const ImSDK = {
     }
 
     const res = await apiRequest<{ content?: ImMessage[] } | ImMessage[]>(
-      `/api/im/messages/history/${encodeURIComponent(groupId)}`,
+      `/api/im/messages/group-history/${encodeURIComponent(groupId)}`,
       { params: { appId: config.appId, page: String(page), size: String(size) } },
     )
     const messages = Array.isArray(res) ? res : (res.content ?? [])
@@ -293,6 +315,18 @@ export const ImSDK = {
     await ImDatabase.markRead(config.appId, targetId)
   },
 
+  async setConversationMuted(targetId: string, _chatType: string, muted: boolean): Promise<void> {
+    if (!ImDatabase.isInitialized()) return
+    const config = getConfig()
+    await ImDatabase.setConversationMuted(config.appId, targetId, muted)
+  },
+
+  async setConversationPinned(targetId: string, _chatType: string, pinned: boolean): Promise<void> {
+    if (!ImDatabase.isInitialized()) return
+    const config = getConfig()
+    await ImDatabase.setConversationPinned(config.appId, targetId, pinned)
+  },
+
   /**
    * Fetch last page of messages for each known conversation from server and save locally.
    * Called automatically after connection is established via login/loginWithToken.